Composition for treatment of water and reconditioning of soils

ABSTRACT

A composition for treatment of water and soils comprises components 
     A. CaCO 3 , 
     B. at least one compound selected from the group consisting of calcium salts, including CaCl 2  and Ca(NO 3 ) 2 , and inorganic magnesium compounds, 
     C. at least one compound selected from the group consisting of NaHCO 3  and KHCO 3 , 
     wherein the components A and B are present in a molar ratio of from 0.1:1 to 1:1, and wherein the components B and C are present in a molar ratio of from 1:3 to 1:1.

BACKGROUND OF THE INVENTION

The present invention concerns a composition for treatment of water,especially standing bodies of water and drinking water, for example,drinking water produced by water treatment plants and for reconditioningof acidic soils.

The preparation of drinking water and purification of bodies of waterpresent an ever-increasing problem in an industrial society.Acidification of waters, meaning that the pH value of the water drops asa result of acidic tributaries, acid rain or through the influx ofacidic components of the soil, is a well known problem. The natural pHbalance of the body of water is disturbed by the low pH, andadditionally, heavy metal salts are quite soluble at lower pH, wherebythe content of heavy metal salts known to have detrimental effects onliving organisms is greatly increased. Moreover, metal water pipes canbe dissolved at low pH values. Overall, a drastic reduction or,respectively, a drastic increase in the pH value of waters, especiallystanding bodies of water, leads to a decrease in the ability of thewater to clean and regenerate itself, and finally to a gradualdegeneration and death.

A further problem is that acidic waters frequently suffer from aninsufficient lime content, a condition which results in furtherweakening of the biological activity of waters.

Furthermore, drinking water with a pH which is too high, or too low,respectively, and an insufficient content of lime can lead to healthproblems.

Frequently, drinking water which is prepared by utilization ofconventional water treatment facilities does not conform to thestandards set by law for pH value, lime content and buffer capacity andthus cannot be released for use by the consumer. According to legalstandards, drinking water should have a pH of between 6.5 and 9.5.

Lime, CaCO₃, is traditionally used to increase the pH value and limecontent of acidic waters. Studies have shown, however, that lime settlesas a layer on the bottom of the body of water and, in this form, doesnot have the desired effect of raising the pH.

In the case of strongly acidic waters, especially those that suffer fromhaving acidic industrial waste waters fed into them, NaOH is usedoccasionally as well. The addition of NaOH only neutralizes the water,however, and causes no improvement in the water hardness or the buffercapacity so that no real positive stimulation of the water is broughtabout.

A further means which is used to raise the pH value of waters and/orsoils is the use of Na₂CO₃, soda. The addition of soda leads to ashort-term success. It does not contribute to an increase in hardness.The risk of damage to organism-bearing sediments due to localover-alkalization is great, however.

The object of the present invention is to provide a composition whichmakes it possible to effect long-term rejuvenation of strongly acidicor, respectively, strongly alkaline waters and soils, especially withrespect to providing a stable pH value in the range between 6.5 and 9.5together with a sufficient hardness.

SUMMARY OF THE INVENTION

The composition for treatment of water and soils according to thepresent invention is primarily characterized by comprising components:

A. CaCO₃,

B. at least one compound selected from the group consisting of calciumsalts, including CaCl₂ and Ca(NO₃)₂, and inorganic magnesium compounds,

C. at least one compound selected from the group consisting of NaHCO₃and KHCO₃,

wherein the components A and B are present in a molar ratio of from0.1:1 to 2:1, and

wherein the components B and C are present in a molar ratio of from 1:3to 2:1.

Preferably, the inorganic magnesium compounds include chloride, nitrate,carbonate, oxide, and sulfate, and the calcium salts and inorganicmagnesium compounds are used in a molar ratio of from 0.8:1 to 10:1.

The calcium salts and inorganic magnesium compounds are expediently usedin a molar ratio of from 1:1 to 6:1.

The components A and B are present in a molar ratio of from 1:1.3 to1.3:1.

The components A and B are present in a molar ratio of from 1:1.3 to1:2.

The component C preferably comprises NaHCO₃ and KHCO₃ in a molar ratioof from 10:1 to 1:1.

The component A further may comprise up to 25 weight-% MgCO₃.

The inventive composition may further comprise Na₂CO₃ in an amount of upto 20% of a molar amount of the component C.

The present invention also concerns a method for treatment of water tobe treated comprising the steps of:

a) dissolving at least one compound selected from the group consistingof calcium salts, including CaCl₂ and Ca(NO₃)₂, and inorganic magnesiumcompounds in H₂O to form a first aqueous solution,

b) dissolving separately at least one compound selected from the groupconsisting of NaHCO₃ and KHCO₃ in H₂O to form a second aqueous solution,

c) mixing the first and second aqueous solutions with the water to betreated to form a mixture, and

d) passing the mixture of step c) over CaCO₃.

Step d) preferably includes the step of providing CaCO₃ as a solid bed.

The invention also relates to a method of treating acidic and alkalinewater to be treated, including drinking water and standing bodies ofwater, said method comprising the steps of:

preparing a composition comprising:

A. CaCO₃,

B. at least one compound selected from the group consisting of calciumsalts, including CaCl₂ and Ca(NO₃)₂, and inorganic magnesium compounds,

C. at least one compound selected from the group consisting of NaHCO₃and KHCO₃,

wherein the components A and B are present in a molar ratio of from0.1:1 to 2:1, and

wherein the components B and C are present in a molar ratio of from 1:3to 2:1; and

adding the composition to the water to be treated.

The invention also relates to a method of treating soils to be treated,including acidic forest soils, said method comprising the steps of:

preparing a composition comprising:

A. CaCO₃,

B. at least one compound selected from the group consisting of calciumsalts, including CaCl₂ and Ca(NO₃)₂, and inorganic magnesium compounds,

C. at least one compound selected from the group consisting of NaHCO₃and KHCO₃,

wherein the components A and B are present in a molar ratio of from0.1:1 to 2:1, and

wherein the components B and C are present in a molar ratio of from 1:3to 2:1; and

adding the composition to the soils to be treated.

DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention thus provides a composition for treatment of waterand reconditioning of soils, comprising

A. CaCO₃,

B. CaCl₂ and/or Ca(NO₃)₂ and, optionally, magnesium salts

C. NaHCO₃ and, optionally, KHCO₃

whereby components A and B are present in a molar ratio of from 0.1:1 to2:1 and components B and C are present in a molar ratio of from 1:3 to2:1.

Surprisingly, it has been found that through use of the composition ofthe present invention in conjunction with waters as well as soils, astable pH value of between 6.5 and 9.5 is achieved, while at the sametime the lime content is increased and a stable buffer capacity isprovided. In general, and even in cases of strongly acidified waters,use of the composition of the present invention resulted in asignificant increase in the microbiological activity of the water, evenafter just a few days. This was even more surprising in view of the factthat component B, namely CaCl₂ or Ca(NO₃)₂ and optional magnesium salts,are themselves acidic when dissolved in water. It was also surprisingthat use of the composition reduces the pH value of high pH waters and,in spite of this, the water hardness and the buffer capacity withrespect to acids increases. It was also determined that metals largelyprecipitate and that colloidally suspended particles are entrapped inthis process as well. Further, it was also observed that aggregates ofhumic acids were formed, whereby the effect of these acids with respectto mobilization of metals was decreased.

The components of the present invention can all be obtainedcommercially, the grades or qualities thus available being suitable forthe invention. Commercially available calcium salts are obtained fromnaturally occurring minerals and can contain small amounts of othermaterials which generally have no influence upon the effectiveness ofthe composition of the present invention. For example, magnesium saltsmay also be present, levels of which correspond to that which arepresent in the naturally occurring source. When the composition is usedfor treatment of drinking water, grades of components with puritiessuitable for this purpose are preferred, especially components ofanalytical quality.

Component A can consist of any commercially available grade of CaCO₃.Freshly precipitated CaCO₃ has been shown to be especially advantageous.When CaCO₃ with a very fine particle size (diameter of about 1 μm) isused, then very low levels (a mole fraction of from 0.01 to 0.1 withrespect to the molar amount of component B) are sufficient. Component Acan contain up to 25 weight per cent MgCO₃. The content of MgCO₃ shouldnot be too high, however, because of the danger of over alkalization,resulting in the set in of decarbonization and subsequent precipitationof lime (water softening). This is diametrically opposed to the purposeof the invention.

Component B can consist of any calcium salt such as calcium chloride orcalcium nitrate or mixtures thereof, whereby calcium chloride ispreferred. Even if the calcium salts demonstrate an acidic pH value whendissolved in water, the addition of this component results in a stablepH value of between 6.5 and 9.5. The choice of calcium salt is notrestricted to special qualities, and thus any commercially availablecalcium salt can be employed. If the composition of the presentinvention is used for reconditioning of soils, the following compositionhas been shown to be particularly advantageous, where B is a mixture ofCaCl₂, up to 10 weight-% Ca(NO₃)₂, and magnesium salts, especiallyselected from the group consisting of chloride, nitrate, carbonate,oxide and sulfate, whereby the molar ratio of the amounts of calciumsalts to magnesium salts can vary in a wide range and is preferably inthe range of 0.8:1 to 10:1, especially preferred being 1:1 to 6:1.

The molar ratio of the amounts of components A and B are as a rule 0.1:1to 2:1, preferably 1:1.3 to 1.3:1. In the case of treatment of alkalinewaters, component B is preferably in excess so that the molar ratiopreferable in this case is 1:1.3 to 1:2.

The third component of the composition is NaHCO₃. Optionally, KHCO₃ mayalso be present as a further component. Commercially available productsof any quality may be used in this case. KHCO₃ is employed especiallywhen low potassium waters and soils are to be treated. In this case, themolar ratio of NaHCO₃ and KHCO₃ is in the range of 10:1 to 1:1. Eventhough KHCO₃ can be used in excess, this is not preferred for reasons ofcost.

Components B and C are present normally in a molar ratio of 1:3 to 2:1,preferably 1:2.3 to 1:1.7, especially preferred being 1:2.1 to 1:1.9.

The composition of the present invention can contain other commonadditives which are traditionally used for water treatment andreconditioning of soils.

In instances where strongly acidic waters or soils are to be treated,the composition of the present invention may also contain limitedamounts of soda, Na₂CO₃. Soda can be added in molar fractions of up to20% based on the molar amount of component C.

The individual components may be added as a mixture or one after anotherto the bodies of water or drinking water, respectively, or to the soil.It is, of course, also possible to apply components B and C and,optionally, the soda and then to distribute component A over the surfaceof the water or soil at a later time.

The composition of the invention can be applied in any manner which isdesirable. With smaller bodies of water or smaller soil surfaces, thecomposition can be distributed by hand. With larger surfaces, mechanicalmeans for distribution, especially means for distributing via the air,have also been shown to be advantageous. For the treatment of drinkingwater, the composition of the present invention can be added to thewater purification process equipment in a practical manner, particularlybefore any mechanical de-acidification or filtration step which mightoccur.

The present invention also comprises a process for the treatment ofwater, characterized in that the steps of the process comprisedissolving components B, CaCl₂ and/or Ca(NO₃)₂ and optionally magnesiumsalts, and C, NaHCO₃ and optionally KHCO₃, separately in water, mixingthe solutions with the water to be treated, and passing the solutionthus obtained over CaCO₃.

In order to preserve the activity of components B and C, it ispreferable to mix components A and B in appropriate molar ratios withwater to be treated, and then to pass the solution over CaCO₃ withoutlong intervening times. In a preferred embodiment, the CaCO₃ is in theform of a calcium bed.

It has also been shown to be advantageous to mix the components B and Cwith the water to be treated in certain molar proportions relative toone another. Preferably, components B and C are present in a molar ratioof from 1:3 to 2:1, preferably from 1:2.3 to 1:1.7, especially preferredbeing from 1:2.1 to 1:1.9. The amount of CaCO₃ utilized while carryingout the process of the present invention is not of significance. Thewater to be treated, containing components B and C, is passed over theCaCO₃. The CaCO₃ dissolves in the water to such an extent that anequilibrium is established with the solution, the excess CaCO₃ remainingin the form of a solid, for example in the solid bed.

The amount of B and C to be added to the water to be treated can becalculated based on the desired hardness and buffer capacity. When amixture of 0.2 mol CaCO₃:1 mol CaCl₂:1.8 mol NaHCO₃ was used in theamount of 100 mg mixture per liter water, a hardness increase of 1.3° dHwas observed. At the same time, the iron concentration dropped from 2.4mg/l in the untreated water to 0.08 mg/l in the treated water. Usingthis particular composition, the conductivity per 100 mg/l increasedabout 115±10 μS/cm. The effectiveness of the water hardening based onthe sum of calcium and magnesium contained in A and B is dependent uponthe condition of the water to be treated.

Depending on need, a treatment using a total of 5-1500 mg/l of thecomposition is especially appropriate. The most frequently used amountslie between 50 and 300 mg/l. In general, the minimum amount useful fordrinking water is between 100 and 200 mg/l.

Furthermore, the present invention comprises the use of the compositiondescribed above for the treatment of acidic and alkaline bodies ofwater, especially standing bodies of water, which are obtained forexample by filtration and employment of traditional water treatmentsystems. The establishment of the lime—carbon dioxide equilibrium occursvery quickly.

The invention further comprises the use of the composition describedabove for the reconditioning of soils, especially acidic forest soils.

EXAMPLES

Field experiments have shown that the composition described aboveprovides a long-term pH value of 8.1 when applied to standing bodies ofwater, namely ponds in city parks and in private gardens.

Additionally, it was shown that already within about three days afterthe application of the composition of the present invention, a turbidityof the water was observed, indicating an increase in the amount ofmicrobiological activity.

Experiments were carried out using a mixture in the followingcomposition range:

A=0.9, B=2.4, C=6.0 (molar ratio of components), corresponding to:A:B:C=1:2.7:6.7, with C=n(NaHCO₃)+n(KHCO₃).

Experimental results are shown in Table 1.

Measured results Concentration used Immed. Total pH pH pH Hardness CaCl₂NaHCO₃ KHCO₃ CaCO₃ hardness alkalinity after after after 48 h No. mmol/l°dH mmol/l mmol/l mmol/l mmol/l °dH mmol/m 2 h 5 h 24 h °dH 1 2.4 13.446.0 0 0.9 0.99 5.5 2.9 7.58 7.62 7.90 8.1 2 2.4 13.44 5.4 0.6 0.9 1.065.9 2.96 7.56 7.61 7.91 8.3 3 2.4 13.44 4.8 1.2 0.9 1.09 6.1 3.01 7.527.59 7.88 8.4 4 2.4 13.44 4.2 1.8 0.9 1.15 6.4 3.27 7.56 7.57 7.83 9.1 52.4 13.44 3.6 2.4 0.9 1.16 6.5 3.43 7.53 7.58 7.87 9.6 6 2.4 13.44 3.o3.0 0.9 1.14 6.4 3.55 7.57 7.60 7.85 9.9 7 2.4 13.44 2.4 3.6 0.9 1.106.2 3.60 7.59 7.62 7.84 10.0 The water temperature was 22° C. for allexperiments.

Variation in the mole fraction of sodium hydrogen carbonate andpotassium hydrogen carbonate, respectively, produced the surprisingresult that the extent of the immediate hardening of the water was mostpronounced at a KHCO₃ mole fraction of 2.4. The lower degrees ofhardening were unusual as well. While pure calcium chloride gives ahardening directly proportional to the amount dissolved in solution, thecomposition of the present invention gives only a partial increase inthe hardness (immediate effect about 40-110%, based on CaCl₂). Thispartial increase in hardness is in contrast to the total alkalinity ofthe solution. Surprisingly, it was determined that, in the process ofreaching an equilibrium of the lime—carbon dioxide system, there was aninitial excess in total alkalinity which quickly fell off in favor of arising total hardness. Because the increase in the total hardness is incontrast to an equivalent portion of the total alkalinity (filteredsolutions!), the water does not demonstrate an increased aggressivenesswith respect to metallic materials in the water pipe system due to thetreatment (increase in Cl⁻ concentration) (C. L. Kruse, Korrosion, VCH).

The pH value increases continually in all cases as a function of time.After about 48 hours, the pH value in every instance was 8.2±0.05. A pHvalue which is constant over time reflects a stable lime—carbon dioxideequilibrium. The opportunity for gas exchange at the solution/airinterface increases the rate at which the equilibrium is established.

Even though almost every composition within the composition rangedescribed was effective in providing a ΔpH value of less than 0.2 andsaturation index of less than 0.2 (measured according to DIN 38404 C10),the mixture of 3 mmol CaCl₂, 6 mmol NaHCO₃ and 0.6 mmol CaCO₃ wasespecially effective in experiments using CO₂-saturated distilled water.The results are shown in the following table:

After After 24 h Initial 1 h c(Ca²⁺) KS4.3 SI; pH pH pH (mmol/l)(mmol/l) ΔpH 4.3 6.98 7.08 3.54 6.33 0.25; 0.16 

During the course of the experiments, the saturation index SI as well asthe ΔpH value rapidly approached the value of 0.10.

Two tons of a mixture of 0.1 mmol CaCO₃:1 mmol CaCl₂:2 mmol NaHCO₃ wasdistributed over a pond with a surface area of 1.44 ha. The hardness wasincreased with an effectiveness of 90%, having a corresponding positiveeffect on the buffering capacity, and the iron content was reduced fromabout 0.55 mg/l to about 0.15 mg/l.

Experiments with CaCl₂—NaHCO₃ and CaCl₂—KHCO₃ systems showed that whencomponent A is not present, the pH value drops continuously with time.These results are shown in the following table 2:

TABLE 2 pH pH pH c(CaCl₂) c(KHCO₃) after 2 h after 5 h after 24 h 2.4mmol/l 6 mmol/l 7.94 7.91 7.81 pH pH pH c(CaCl₂) c(NaHCO₃) after 2 hafter 5 h after 24 h 2.4 mmol/l 6 mmol/l 7.92 7.91 7.83

Establishment of a equilibrium is facilitated by using freshlyprecipitated quality of CaCO₃. Without addition of this solid phase,comparable equilibrium conditions were not reached.

The present invention is, of course, in no way restricted to thespecific disclosure of the specification and drawings, but alsoencompasses any modifications within the scope of the appended claims.

What is claimed is:
 1. A composition for treatment of water and soilsfor providing a stable pH of between 6.5 to 9.5, increasing the limecontent, and providing a stable buffer capacity, said compositionconsisting of components A. CaCO₃, B. at least one compound selectedfrom the group consisting of calcium salts and inorganic magnesiumcompounds, C. at least one compound selected from the group consistingof NaHCO₃ and KHCO₃, and D. NaCO₃ in an amount of 0 to 20% of a molaramount of the component C, E. optionally water treatment additives orsoil reconditioning additives, wherein the components A and B arepresent in a molar ratio of from 0.1:1 to 2:1, and wherein thecomponents B and C are present in a molar ratio of from 1:3 to 2:1.
 2. Acomposition according to claim 1, wherein: the inorganic magnesiumcompounds are selected from the group consisting of chlorides, nitrates,carbonates, oxides, and sulfates; and calcium salts and inorganicmagnesium compounds are used in a molar ratio of from 0.8:1 to 10:1. 3.A composition according to claim 2, wherein calcium salts and inorganicmagnesium compounds are used in a molar ratio of from 1:1 to 6:1.
 4. Acomposition according to claim 1, wherein the components A and B arepresent in a molar ratio of from 1:1.3 to 1.3:1.
 5. A compositionaccording to claim 1, wherein the components A and B are present in amolar ratio of from 1:1.3 to 1:2.
 6. A composition according to claim 1,wherein the component C comprises NaHCO₃ and KHCO₃ in a molar ratio offrom 10:1 to 1:1.
 7. A composition according to claim 1, wherein thecomponent A further comprises up to 25 weight-% MgCO₃.
 8. A compositionaccording to claim 1, wherein said calcium salts are CaCl₂ and Ca(NO₃)₂.9. A method for treating water to provide a stable pH of between 6.5 to9.5, increase the lime content, and provide a stable buffer capacity,said method comprising the steps of: a) dissolving at least one compoundselected from the group consisting of calcium salts and inorganicmagnesium compounds in H₂O to form a first aqueous solution, b)dissolving separately at least one compound selected from the groupconsisting of NaHCO₃ and KHCO₃ in H₂O to form a second aqueous solution,c) mixing the first and second aqueous solutions with the water to betreated to form a mixture, and d) passing the mixture of step c) overCaCO₃.
 10. A method according to claim 9, wherein step d) includes thestep of providing CaCO₃ as a solid bed.
 11. A composition according toclaim 9, wherein said calcium salts are CaCl₂ and Ca(NO₃)₂.
 12. A methodof treating acidic and alkaline water for providing a stable pH ofbetween 6.5 to 9.5 increasing the lime content, and providing a stablebuffer capacity, said method comprising the steps of: preparing acomposition consisting of: A. CaCO₃, B. at least one compound selectedfrom the group consisting of calcium salts and inorganic magnesiumcompounds, C. at least one compound selected from the group consistingof NaHCO₃ and KHCO₃, and D. NaCO₃ in an amount of 0 to 20% of a molaramount of the component C, wherein the components A and B are present ina molar ratio of from 0.1:1 to 2:1, and wherein the components B and Care present in a molar ratio of from 1:3 to 2:1; adding the compositionto the water to be treated; and optionally adding water treatmentadditives or soil reconditioning additives.
 13. A composition accordingto claim 12, wherein said calcium salts are CaCl₂ and Ca(NO₃)₂.
 14. Amethod of treating soils for providing a stable pH of between 6.5 to9.5, increasing the lime content, and providing a stable buffercapacity, said method comprising the steps of: preparing a compositionconsisting of: A. CaCO₃, B. at least one compound selected from thegroup consisting of calcium salts and inorganic magnesium compounds, C.at least one compound selected from the group consisting of NaHCO₃ andKHCO₃, and D. NaCO₃ in an amount of 0 to 20% of a molar amount of thecomponent C, wherein the components A and B are present in a molar ratioof from 0.1:1 to 2:1, and wherein the components B and C are present ina molar ratio of from 1:3 to 2:1; adding the composition to the soils tobe treated; and optionally adding water treatment additives or soilreconditioning additives.
 15. A composition according to claim 14,wherein said calcium salts are CaCl₂ and Ca(NO₃)₂.